Method for automatic moisture control in foundry sand supplies



Nov. l, 1960 N, HARTLEY 2,958,107 METHOD FOR AUTOMATIC MOISTURE CONTROL i 1N FOUNDRY SAND SUPPLIES Original Filed March 29, 1952 7 Sheets-Sheet 1 N0V- l, 1960 N. HARTLEY 2,958,107

METHOD FOR AUTOMATIC MOISTURE CONTROL 1N FOUNDRY SANO SUPPLIES Original Filed March 29, 1952 7 Sheets-Sheet 2 INVENTOR /VE/sm/ Her# BY www@ ATTORNEYS Nov. 1, 1960 N HARTLEY 2,958,107

METHOD FOR AU'OMATIC MOISTURE CONTROL IN FOUNDRY SAND SUPPLIES Original Filed March 29, 19512 7 Sheets-Sheet 3 INVENTOR /VELsa/v #Me/25V ATTORNEYS .AIU Nov. l, 1960 N. HARTLEY 2,958,101

METHOD FOR AUTOMATIC MOISTURE CONTROL IN FOUNDRY SAND SUPPLIES Original Filed March 29, 1952 7 Sheets-Sheet 4 IN VENTOR NEL sa/v Hazme-V BY MMIAMM A TTORNEYS N0 l, 1960 N. HARTLEY 2,958,107

METHOD FOR AUTOMATIC MOISTURE CONTROL In FouNDRY smo SUPPLIES original Filed laren 29, 1952 v sheets-sheet 5 a4 1f. /Qf e l e rf: i hgg-l y /o g INVENTOR NELsa/v #Her-5V J7' l] ATTORN E YS Nov. 1, 1960 N. HARTLEY 2,953,107

METHOD FOR AUTOMATIC MOISTURE CONTROL IN FOUNDRYSAND SUPPLIES Original Filed llarch 29, 1952 7 Sheets-Sheet 6 J5 2 i m m. 1:51. f w g ,47 /53 /e/ v l ll l I L M g e ".l 50:. .'O; A, 4 r /zz /50 if Il /75 i a3 l j 7 /79 j /55 /5 Q /5/ 2 /78 lmfql. F.l mud Uu/k, u Hf d ,55 /75 /45 we) ,ha

INVENTOR e "fw /VELoN Hanne-Y BY Mar-LM ATTORNEYS Nov. 1, 1960 N. HARTLEY 2,958,107

METHOD FOR AUTOMATIC MOISTURE CONTROL IN FOUNDRY SAN.) SUPPLIES Original Filed March 29, 1952 7 Sheets-Sheet 7 INVENTOR /VELso/v Hna rus ATTORNEYS METHOD FR AUTOMATC'MGISTURE CONTROL IN 'FOUNDRY SAND 'SUPPLIES Nelson Hartley, Baltimore, Md., assigner to Hartley Controls Corporation, a corporation of Wisconsin Original application Man 29, 1952, Ser. No. 279,369,

now Patent No. 2,709,843, dated June 7, 1955. Divided and this application May 5, l1955, Ser. Nc.

7 claims. (0122-217) This invention relates to a method for automatic moisture control in foundry sand supplies. The present application is a division of my application 279,369, iiled March 29, 1952, lnow Patent 2,709,843, entitled Device for Supplying to a Foundry Sand Mixer Water and Sand in Automatically Predetermined Proportions According to Sand Temperature. Cross reference is also made to my `application 448,201, filed August 6, 1954, and entitled Completely Automatic Supplying, Mixing, Moisture Control, and Delivery of yFoundry Sand.

In foundry sand practice, the amount of Water required should depend in part upon the original moisture content of the sand and in part upon the sand temperature. It is important that the sand and the moisture be automatically proportioned to each other in advance of delivery into the mixer. While this may be done in a continuous operation, the sand :and the Water may also be measured in separate and correlated batches which are then dumped concurrently into the mixer and mixed While a subsequent batch of sand and a correlated batch of water are being measured.

In the drawings:

Fig. 1 is a view largely in front elevation and partially in section which diagrammatically shows the entire organization.

Fig. 2 is an enlarged detail View in vertical section through the water measuring tank and the discharge valve therefrom.

Fig. 3 is a view in front elevation on a reduced scale showing a modified water measuring tank arrangement, which makes a discharge valve unnecessary.

Fig. 4 is an enlarged view partially in front elevation and partially in transverse section through the integrating device.

Fig. 5 is a view taken in horizontal section on the 5 5 of Fig. 4.

Fig. 6 is a view taken in horizontal section on the line 6-6 of Fig. 4.

Fig. 7 is a View principally in front elevation and partially in section of the temperature responsive apparatus in the integrating device of Fig. 4.

lFig. 8 is a view largely in front elevation and partially in section of the water volume responsive device in the integrating mechanismshown in Fig. 4.

Fig. 9 is a view in front elevation on a reduced scale showing the control cabinet in which the integrating instrument of lFig. 4 is desirably mounted.

IFig. 10 is a diagrammatic view partially in elevation and partially in section showing a modied arrangement in which the moisture of the returning sand, as well as its temperature, determines the amount of water automat- Iically added.

Fig. 11 is a view partially in side elevation and partially in section illustrating a train of `driving connections used in the embodiment of Fig. l0.

Fig. 12 is a detail plan view from the viewpoint indicated by the line 12-12 in Fig. 11.

Fig. 13 is a view on the line 13-13 of Fig. 11.

Fig. 14 is a view taken on the line 14-14 of Fig. 11.

Fig. l5 is a circuit diagram of the electrtical connections used in the embodiment shown in Figs. 10 to 13, inclusive.

Fig. 16 is a diagrammatic view partially in side elevation and partially in section showing a modified embodiment of the invention.

Fig. 17 is a diagrammatic view of a further modified embodiment of the invention.

Fig. 18 is a diagrammatic view of another modified embodiment of the invention.

Assuming that the device is to be used for the integrated measuring of batches of sand and water for delivery to a foundry sand mixer, a conventional mixer has been shown diagrammatically at 10 arranged for discharge on to a conveyor 11. The mixer itself forms no part of the present invention. It is provided with a water inlet at I12 and a sand receiving hopper 13.

The previously used foundry sand, together with any increments required to make up losses, is stored in astorage bin 14, the discharge from which is controlled by the valves 15 which are intergeared 4and operated by a double-acting pneumatic cylinder 16, the piston rod 17 of which is connected to one of the valves.

Arranged to receive the sand discharged past valves 15 from the storage bin y14 is the measuring hopper 18, which may discharge directly into the sand-receiving inlet 13 of the mixer, subject to the control of valves 19 which are similar to valves 15, being intergeared and operated by the piston rod 2t) of adouble acting pneumatic cylinder 21. The discharge end of the storage bin 14- desirably extends into the measuring hopper 18 so that the delivery of sand will automatically cease Vwhen the level of the sand 22 in the measuring hopper 18 reaches the outlet of bin 14, regardless of the position of the valves 15.

The pneumatic actuating cylinders are supplied with air by means of pipes 23, 24 which are oppositely connected to the respective ends of the cylinders 16 and 21 so that the valves 15 and 19 will work in alternation, valves 15 being open when valves `19 are closed, and vice veresa. The pipes 23, 24 are connected with the air supply line 25, and alternatively with the vent 26 by means of a rotary valve 27 which is diagrammatically shown in Fig. l and is manually operated, so that the operator in charge of the mixer can deliver to the mixer, whenever it is empty, a charge of sand 22 accumulated in the measuring hopper 18 while the previous charge is being mixed.

-T he water required for the addition of sand accumulated in the measuring hopper 18 is accumulated in the water measuring tank 30 from a Water supply line 31 controlled by an electro-magnetically operated valve at 32. A float 33 within the tank rises as the water enters the tank and communicates motion by means of rack 34 and pinion 35 through the :beveled gears 36, 37 and iiexible shaft `38 to an integrating device hereinafter to be described, whereby the flow of water is cut off when an amount has been stored in tank 30 which is properly correlated with the amount and temperature of the sand 22 in the measuring hopper 18.

When the air control valve 27 is manipulated to dump the sand, the water is pneumatically released from tank 30 and dumped into the water inlet 12 of the mixer 10. As shown in Fig. 2, this is accomplished by admitting air pressure from pipe 23 through branch pipe 39 to the air cylinder 40 to lift nthe piston 41, therod 42 of which lifts valve 43 from its seat 44. The pins 45 with which the valve is provided, as shown in Fig. 2, are merely guides within the delivery pipe 46 to assure the proper resetting of the valve seat.

The large diameter of pipe 46 will be observed. I have found that if the water is introduced in small volume into the mixer, the wet sand will tend to encrust the walls of the mixer, whereas if the entire volume of water 4is dumped into the mixer as rapidly as possible, the walls of the mixer will tend to remain clean.

When all of the water and all of the sand has been discharged from tank 30 and measuring hopper 18 into the mixer 10, the operator will reverse the position of valve 27 to admit air to the pipe 24, whereby valve 19 will be closed and valve opened. The air communicated through branch pipe 47 to the upper end of the air cylinder 40 will re-close the water valve 43 in the water measuring tank 30.

Fig. 3 shows an alternative arrangement whereby no outlet valve on tank 30 is required. The pipe 46 is provided with a gooseneck or trap which, at 48, is higher than the maximum level of water to be measured in tank 30. Water will be held by gravity in the tank until the valve 27 admits air from the pressure line 25 to pipe 23. Thereupon the admission of such air through the branch pipe 39 to the interior of tank 30' creates a head upon the water in the tank which causes it to flow over the gooseneck 48 and down through pipe 46 to the mixer 10. The arrangement is regarded as equivalent to that shown in Fig. l and Fig. 2 in that it releases the water into the mixer substantially co-incidentally with the release of sand, and uses pneumatic pressure for that purpose.

'I'he integrating apparatus now to be described measures the amount of water ilowing into tank 30 to provide a primary amount which is independent of sand temperature and a secondary amount which is proportioned to sand temperature. In its preferred form, the apparatus comprises a dial with pointers so that the operator can observe the operation. The actual integration, however, is independent of the dial and of the pointers which are visible to the operator.

Ihe instrument comprises a thermometer of the remote bulb type. The bulb 50 is supported on a cross member 51 in the sand measuring hopper 18 where it is exposed to the sand flowing into the hopper and to the sand which has accumulated therein. The bulb commnicates through an armored tube 52 with a KBourdon tube 53 in the instrument case 54 shown in Figs. 4 to 6. At the end of the Bourdon tube is an actuating arm 55 connected by link 56 with a composite lever comprising parts 57 and 58, each of which is pivoted on the pintle 59, the two parts being adjustably connected for calibration purposes by means of a bolt 60. The pivotal connection between link 56 and lever element 57 is desirably made adjustable also, the adjustment being provided by making the pivot bolt `61 adjustable longitudinally of the lever in the slot 62.

'Ihe lever '57, 58 carries a segment 63 meshing with the pinion 64 on a quill shaft 65 which carries a pointer 66. The pointer 66 operates over a dial `67 which may be calibrated in terms of temperature. This is for the benetit of the operator. The actual integration, however, is performed by an integrating element which comprises a nger 70 connected with the lever 57, 58 as shown Iin Figs. 4, 6, 7 and 8.

The shaft 38 which is rotated by the movement of the float 33 within the water measuring tank 30 drives Within the meter casing 54 a worm shaft 71 mounted in bearings in bracket 72 (Fig. 4) and carrying a worm 73 at its lower end. This worm meshes with the worm gear 74 mounted on a shaft 75 which projects from the casing and is provided with a knob at 76. Within the casing it carries a pointer 77 movable over a dial 78l which may be calibrated in gallons. Immediately behind the pointer, the shaft 75 is rotatably and slidably mounted in brackets 79, and at its rear end it is Vsimilarly mounted in beaning 80 fixed to the rear wall of the meter case. A compression spring 81 urges shaft 75 rearwardly in its bearings. Between bearing 80 and worm gear 74, this shaft carries a pinion at 82 meshing with a gear 83 which has an arm 84. This arm has a lost motion connection with link 85 by means of a bearing pin 86 screwthreaded into arm 84 and movable freely for the length of slot 8,7 with which the link 85 is provided.

The link, when the pin y86 reaches the end of slot 87, transmits motion to a lever y88 pivoted on the rod 59 and supporting a sensitive switch at 90 from which projects the oscillatory switch actuator 91 into the path of movement of the linger 70. The switch contacts (not shown) of switch 90 are normally closed and are opened by the actuator 91 when the actuator and lthe linger 70 are engaged as a result of the upward movement of the switch or the downward movement of the finger.

In order to give a visual indication of switch position, the lever 88 has an extension 93 which carries a segment 94 meshing with the pinion `95 on shaft 96. This shaft extends through the quill shaft 65 .to the front of dial 67, where it carries a pointer 98. The position in which the pointer 98 registers with pointer 66 is the position in which the engagement of linger 70 and switch actuator 91 opens the circuit through switch 90.

`Connected to the terminals of switch 90, as shown in Fig. 4, are conductors 99 and 100. The wiring circuit is diagrammatically included in Fig. l.

In series in one side 101 of the line is the instrument switch 102, the opening of which opens the entire circuit. This switch connects with conductor leading to the micro switch 90 within the instrument case. It also supplies through conductor 103 and conductor 104 a switch 105 which is manually operable to permit the operator to add water without reference to the integrating device. Another branch of conductor 103 leads via conductor 106 to the contact 107 of a relay which, when contact 108 is closed by means of solenoid 109, serves lto energize the coil 110 of the electromagnetic valve 82, the return side of which is connected through conductor 111 with the other side 112 of the line.

A branch conductor 113 leads from conductor 111 through a pneumatic pressure switch 115 to conductor 116. In series therewith is a resistor 117 connected by conductor 118 with the iilament 119 cf an electronic tube 120. The other side of filament 119 is connected by conductor 121 with conductor 99 to be energized through the micro switch 90 in the instrument casing. One of the plates 122 of tube 120 is connected witih conductor 121 by a branch conductor 123. rlhe other plate 124 is connected by conductor 125 with one of the contacts of the manually operable switch 105 and also with the coil 109 which energizes the relay switch 108, 107. The coil 109 is then connected by conductor 126 back to conductor 111 and to the return side 112 of the line.

It is the purpose of the electronic tube 129 to provide a controlled delay in the admission of water into tank 30, to ensure that the finger 70, comprising the integrat- Aing element actuated by thermostatic bulb 50, will have time to reilect with accuracy the temperature of the sand 22 in the measuring hopper 18. The operation is as follows:

The operator first sets the device to predetermine what amount of water is to be added to a batch of sand regardless of temperature. He indicates this amount of water dit by' pulling forwardly on the knob 76 to disengage the worm gear 74 from the worm 73. The length of pinion 82` permits this pinion to slide freely in mesh with its driven gear 83. With. the worm gear disengaged from the worm, the knob is used to rotate shaft 75 to move the pointer 77 over the dial 78 until its indicates on the dial the number of gallons which are to be added regardless of temperature. The knob is then pushed in toV reengage the worm gear with the worm. The adjustment thus made will locate the driving pin 86 of the arm 84 on driven gear 83 at some intermediate point inthe slot 87 as shown in Fig. 4. When the manually operable Valve 27V is in the position shown in Fig. 1, whereby pressure is admitted to the line 24, to admit sand from the storage bin 14 into the measuring hopper 22, the pressure communicated to the pressure switch 115 closes a circuit throughV such switch and resistor 117 and the filament 1-19 of electronic tube 120 and thence through the normally closed contact of switch 90 ot the other side` of the line. The heating of filament 119 requires, in. actual practice, about a half a minute, thereby allowing plenty of time for the thermostatic bulb 50 toy reach the temperature of the sand admitted to the measuring hopper 18. The temperature of the sand, and thek resulting response of the Bourdon tube 53 adjusts the lever 57, 58 and the integrating linger 70 to a given position which is indicated on the dial by the pointer 66'.

Assoon as the filament 119 of tube 120 heats up, current :flowing between the plate elements 122 and 124 of the tube will energize the relay coil 109 to contact 108 to contact 107, thereby providing la power circuit to the coil 11'0 of the electromagnetic valve 32 to open such valve and allow the water to flow into the water measuring tank 302 As the tank fills, the motion of float 33 is communicated through the ilexible shaft 38 to the instrument case Where the worm 73 is rotated in mesh with worm gear '74 to move the pointer 77 back towardV zero and to rotate gear 83. Not until the pointer 77 reaches the zero mark, thus indicating that the entire primary quantity of water has been delivered to the water measuring tank, is any motion communicated from the driving pin 86 at the end of arm `84 to actuate link 85. Up to` this point, the pin 86 has been moving idly in slot 87.

When the entire predetermined quantity of primary water has been delivered into the tank, the pin 86 reaches the endY of slot 87 and the link 85 is actuated to tilt the lever 88 fand thereby bodily to move the switch 90. At the same time, the pointer 98 moves over the face of the dial toward registry with the temperature indicating pointer 66. When the two pointers register, the nger 70 connected with the temperature pointer will encounter the actuator 90 to connect with the link on switch 90 and thereby with the water volume pointer. The engagement of the integrating elements comprising finger 70 and switch actuator 91 opens the normally closed contacts of switch 90 to break the circuit to the relay, whereupon the electromagnetic valve 3?.y closes to cut off further iiow of water.

The operator now has at his disposal a measured batch of sand and a batch of water which has been accurately measured by the integrating mechanism above described, to be the correct amount to provide primary moisture for the sand and to provide secondary moisture in proportion to sand temperature, whatever that may be.

This eliminates the skill heretofore required to proportion water' and sand for a foundry mixture and enables even an unskilled operator to mix successive batches, regardless of sand temperature, to exactly the requiredr consistency.

Despite automatic temperature control of secondary Water, the embodiment thus far described requires manual presetting to determine the amount of primary moisture to be added. Particularly in the event that the moisture content' has material fluctuation, it is appropriate to set the primary water supply automatically as suggested in Fig. 10 and other views presently to be described.

In the construction shown in Figs. 10 to 15, inclusive, electrodes 130, 131 are mutually spaced in the batch hopper 18 and are so connected in circuit with an indicating device or devices, and a suitable supply of current, that the electrical resistance of the sand between the electrodes will be measured as an index of its dryness. The wetter the sand, the greater will be its electrical conductivity and the smaller will be the amount of primary water required. Therefore, the electrical resistance of the sand is used to predetermine that amount of water which is supplied to the accumulating tank 30 prior to the addition of such water as is used to compensate for high temperature. Referring to the circuit diagram in Fig. 15, the secondary 132 of transformer 133 is connected by lead 134 with clectrode130. The other terminal of secondary 132 is connected through rectifier 135 to a relay coil 136; This coil is inv series with relay coils 137, 138, and 139, which are similar except that they are wound to attract the respective armatures 140, 141, 142 and 143 at successively higher current flow. The conductor 141 connects the series-connected relay coils to electrode 131 so that when wet sand intervenes between electrodes and 131 a circuit is completed from the secondary 132 of transformer 133` through the several coils.

When suiiicient iiow of current occurs to induce reaction of armature 140, the movement of this armature toward the coil 1-36 closes the circuit from' the supply line 144 to contact 145, this being connected by conductor 146 to relay coil 147 and thence by conductor 148 to the other side of the supply line 149. Energization of coil 147 attracts the solenoid armature 150` into engagement with step 151 for actuation of lever 175 (Fig. 11) with results hereinafter to be described.

When the ilow of current in electrode 130' and 131 reaches a slightly higher value, such flow through the series connected coils 136,` 137, 138 and 139 will cause armature 141 to be attracted by coil4 137. This will close a circuit to contact 152y whereby in a manner similar to that already described, the relay coil 153 will be energized. In addition to lifting the armature 154 and step 155 of lever 175, such energization will cause an arm 15e of armature 154 to close a switch at 157 which connects line 158 with the conductor 159 between relay coils 136 and 137. The effect of this is to short the relay coil 136 out of the circuit, leaving only coils 137, 138 and 139 in series.

Similarly, a higher flow of current between the electrodes will cause armature 142 to respond to coil 138 thereby closing the circuit through contact 160 to relay coil 161 to attract the armature 162 to actuate step 163 of lever 175. Armature 162, in responding to the energization of itsy coil 151, closes a switch at 164 which shorts relay `coils 137 and 138 out of the circuit, leaving only coil 139. Another arm 165 carried by armature 162 closes a switch at 168 which acts as a holding circuit for relay coil 161 to keep this coil energized even when coil 138 becomes deenergized.

The fourth relay coil 139, has a resistance such that its armature 143 is the last to be attracted. This armature does not respond during any normal functioning of the device but, in the event of a short circuit, or the presence of water in amounts exceeding that which the apparatus is capable of handling, the ilow of current between the electrodes will become high enough so that armature 1'43 will be attracted to engage contact 170, thereby lighting the warning lamp 171. The several relay coils 147, 153, and 161 also have telltale lights at 172, 173, and 174,' respectively, to give visual indication to the operator that the respective coils are functioning.

As clearly shown in Fig. 13, which shows the position of the parts with all of the coils 147, 153 and 161 de- 7 energized, the respective nuts 177, 178 and 179 which are adjustable on the armature rods 150, 154, and 162, are normally spaced at different distances below the steps 151, 155, and 163 of lever 175, thereby to provide different degrees of lost motion in the operation of the lever. The nut 179 is Virtually in engagement with step 163, while nut 178 is spaced below step 155, and nut 177 has increased spacing below step 151. Thus, when armature rod 150 is elevated as shown in Fig. 14, it will actuate lever 175 suciently to increase the spacing between nut 178 and step 155 to approximately the same space which originally existed between nut 177 and step 151. The space between nut 179 and step 163 now corresponds substantially with the space between nut 178 and step 155 in the original de-energized position of the parts.

When coil 153 is now energized, its armature bar 154 will engage step 155 to raise it, and lever 175, to the dotted line positions of Fig. 14, thereby establishing full spacing between nut 179 and step 163. Thus the three armature bars, all having identical strokes will, upon being attracted by their respective solenoids, eifect corresponding increments of travel of the lever 175, the lost motion compensating in each case vfor the fact that the three armatures must act :successively on the same lever.

As best shown in Fig. l1, the lever 175 has its initial position determined by an adjustable stop 180 from which the lever is upwardly oscillatable in the successive increments aforesaid about a pintle 182. Beyond the pintle, the lever is slotted at 183 for adjustment of pivot bolt 184 whereby link 185 is connected to lever 175. At its upper end, link 185 is connected by pivot bolt 186 with lever 841 which, instead of being fixed to gear 83 like the arm 84 (Fig.V 4), is pivoted to the gear upon pivot bolt 187. lt will be remembered from the previous description of the device shown in Fig. 4 that oat operated driving connections rotate gear 74 and shaft 75, the latter carrying the pinion 82 shown in Fig. 12, as well as in Fig. 4 and Fig. 5. Thus, the oscillatory position of the segment or gear 83 is a function of the amount of water in the measuring tank 30. Assuming the lever 175 (Fig. 1l) to be stationary, the rising of the float will transmit motion through pinion 82 and gear 83 to lever 841 to elfect the same movement of such lever as if the lever were xed to the gear 83, as is lever arm 84 in Fig. 4. The movement is the same because, in the assumed stationary position of lever 17S, the pivot bolt 186 at the inner end of lever 841 substantially coincides with the axis of the gear or segment 83. Thus, in the to and fro movement of gear or segment 83, motion is communicated in the Fig. 11 device from the gear through lever 841 to link 851 to oscillate lever 88 and switch 90 exactly as previously described, movement also being communicated to the pointer 98.

The diierence lies in the fact that whereas the gear 83 was, in the previously described construction, manually preset to determine the amount of primary water to be added, the presetting is now done automatically by the resistances and the electrical circuit above described, whereby the lever 175 is tilted from its de-energized position of Fig. l2 to vary the position of lever 841 respecting gear 83, and thereby to vary the datum prosition `of switch 90, lever 88, and pointer 98. Ordinarilv the resistance measuring circuit will have made the adjustment of the lever system preliminary to the introduction `of water into the measuring tank 30 and the consequent response of the float and the float operated gear 83. However, the integrating action tof the device is such that it makes no difference whether the electrical system functions prior to, or simultaneously with, the movement of gear 83; in either case the position of pointer 98 and switch 40 will be a function of the moisture that is in the sand and the water admitted to tank 30; and the effect, is in the manually set device, is to determine the amount of primary water which is added prior to the addition of secondary Water to compensate for sand temperature. Y

In the device shown in Fig. 4, the pivot bolt 86 is adjustable in slot 87. In'the present device, the pivot bolt S61 is not only adjustable in slot 871 of link 851, but also in the slot 842 of lever 841. This, together With the adjustment in radius of connection of link 185 with lever 175 provides very accurate control. `Once the adjustment is determined, the device Will accurately respond to water content of the sand to provide for the desired primary water. To prevent overrun, due to the abrupt action of the solenoids on lever 175, it is desirable to control the movement of lever 175 with a dash pot 193, the plunger 194 of which is connected by link 1951with lever 175.

Some of the features herein described are usable independently `of :others and for diierent purposes within the contemplation of the invention. As suggested in Fig. 16, the electrodes and 131 may be used in a hopper 200 which contains sand at 201 for delivery to a concrete mixer 202. The electrodes are connected in circuit with any suitable current source 203 and a meter 204, the scale 205 of which may be calibrated in gallons. The position of the pointer 206 will be determined by the moisture already present in the sand 201, the pointer moving counterclockwise in response to an increase `of moisture from minimum to maximum. Thus, assuming the scale 205 to show an increase in gallons in a clockwise direction, the eiect of moisture already present in sand will be to reduce the reading on scale 205 of water to be added.

The operator can manually open and close the valve 207 to admit water from supply pipe 208 to the concrete mixer 202 until the Water meter 209 shows that the number of gallons added is the number of gallons indicated by pointer 206 on scale 205, whereupon the operator will close valve 207.

A similar principle of manual control may be used for integrating temperature and initial water content as shown in Fig. 17, which may be assumed, for example, to be a foundry sand handling device. The hopper 18 is identical with that of Fig. l0, having a thermostat 50 and electrodes 130 and 131 and discharge valves 19. The thermostat 50 connects with Bourdon tube 53, the arm 55 of which is connected by link 56 with lever 570, as in Fig. 4. The segment 63 at the end of lever 570 meshes with pinions 64 and 64' to oscillate dial 670, bearing a scale calibrated in gallons or pounds. Pointer 66 is the indicating portion of milliammeter 210, which is connected in circuit between power source 203 and electrodes 130 and 131, as above described. The arrangement is such that dial 670 oscillates counterclockwise in response to an increase in temperature of thermostat 50, and pointer 66 likewise `oscillates counterclockwise in response to an increase in current flow between electrodes 130 and 131, consequent upon high moisture content of the sand in hopper 18. Thus a high moisture content in the sand will reduce the water requirement shown by pointer 66 and dial 670, Whereas a high temperature will tend to increase the water requirement shown by the cooperative action of the pointer and dial.

The operator manually controls valve 207 to deliver water from supply pipe 208 to an amount indicated by water meter 209, the water being delivered into a measuring tank 30 like that shown in Fig. 10 and Fig. l and Fig. 2. However, the discharge valve 212 from tank 30 may, in this instance, be manually controlled.

Fig. 18 shows a modication which may be incorpor- -ated either in the device of Fig. l or that of Fig. l0. Instead of measuring the water after it arrives in tank 30, it measures the water `as it enters the tank by passing it through a meter 209', as in Figs. 16 and 17. In this instance, however, instead of requiring the operator to read the meter, the meter pointer shaft 215 is connected to the tlexible shaft B8 leading to the integrating asador device. With the meter set to zero at the commencement of each operation, it will be evident that when a required amount of water has passed through the meter into tank 30, the operation of the ilexible shaft will cut off the flow in the same manner as if the flexible shaft were driven by the oat type meter 33, as above described.

While the completely automatic operation described in connection with Figs. to 15, inclusive, and Fig. 18 is preferred, the devices of Figs. 16 and 17 will demonstrate the fact that the method involved may be practiced manually if desired. It is further intended to demonstrate, with particular reference to Fig. 16, that portions or all of the apparatus are useful for purposes other than foundry sand handling, it being intended that the various mechanisms may be employed in any combination for the handling of any appropriate material.

My improved method includes the measuring of the water content of Sand as -a guide to the amount of Water to be added thereto, whether the sand is to be used for foundry sand purposes or for concrete or for other purposes. Where foundry sand is involved, my method further contemplates the use of two separate factors in determining the amount of Water, the irst being based on the water content already present in the sand and the second being based on the temperature of the sand. If the water content of the returning sand is fairly constant, the primary water may be added in xed amount, the only variation being in the water which compensates for high temperature.

The actual amount of moisture to be added varies widely according to the composition of the sand and the purposes for which it is to be used. Anyone skilled in foundry sand requirements can set up the apparatus herein disclosed to deliver the requisite amount of water to the sand and, moreover, to integrate original moisture and temperature factors so that the amount of water will still remain correct notwithstanding variations in moisture or temperature of the returning sand. For example, let it be assumed that the plant uses a No. 3 Simpson mixer and that the sand used has both sea coal and bentonite mixed With it and it is desired to operate normally at about 4% moisture. With the base water pointer 77 set at 8 as shown in Fig. 9 and the temperature pointer 66 set at 80 on the scale shown in Fig. 9, the return sand being entirely dry, eight gallons of water would be put into the tank 30 as the result of the setting of pointer 77, bringing the water indicator pointer 9S approximately to the 50 mark on the scale shown in Fig. 9. As water continues to flow into tank 30, the continued movement of pointer 98 will bring it into registry with pointer 66 at the assumed setting of the latter when approximately two additional gallons of Water have been introduced into the tank. Water ilow into the tank will then cease.

If the next batch of sand remains at 80 but the returning sand has one-half of one percent moisture, the pointer 98 will automatically be advanced to a scale reading of about 65 and only about nine gallons of water will enter the tank. On the other hand, if the sand is returning at a temperature of 170 F., the pointer 66 will move to a scale reading of 170 on the scale shown in Fig. 9 and six additional gallons of Water would be added to the tank to make a total of sixteen gallons before the pointer 98 would register with the pointer 66 in the new position of the latter. This assumes that the gear 3S (Fig. 2) is a twenty tooth gear which adds approximately one gallon of water for every rise in temperature, when used in the apparatus shown. The specific amount of decrease of water addition per unit of return sand moisture can be controlled by adjusting the nuts 177, 178, 179 (Fig. 3 and Fig. 4).

It will be understood that the example given is purely illustrative, since different foundry operators use different sand mixtures and have diiferent moisture requirements. All of these can be met automatically and without a skilled operator in attendance once the apparatus herein disclosed is set up to integrate the initial moisture and initial temperature of the sand as herein disclosed. Moreover, once the device has been calibrated, changes in percentage of moisture may be made at will to meet day to day requirements without affecting in any way the continuous integrating operation. Only a change in the initial position of pointer 7 is required.

A further feature of the method invention, as applied to foundry sand, consists in the segregation of the measured Water required for addition to a given batch of sand and the abrupt dumping of the measured batch of water abruptly into the mixture with the sand, as distinguished from the slow trickling of water into previously present sand. As noted above, I avoid incrustation of the mixer by accumulating the water in the process of measurement thereof and then dumping the measured batch of water into the sand. A most important advantage inthe abrupt introduction of water is the immediate reduction of temperature of sand in the mix.

I claim:

1. A method of preparing foundry sand for use with absolute water requirements at atmospheric temperature, said method comprising the step of measuring the super heat of the sand in advance of adding any water thereto, the step of measuring the initial water content of the sand in advance of adding any water thereto, the step of integrating said measurements and the addition to the sand of a quantity of water determined by said integration and which is in direct proportion to its super heat and in inverse proportion to its initial moisture, and mixing with the sand the water so added.

2. The method according to claim l for delivering a proper amount of mositure to foundry sand in a mixer, such method including the further steps of accumula-ting a batch of foundry sand for the mixer, separately accumulating water for delivery to the mixer and measuring said Water to provide integrated quantities of water respectively related inversely of the water content of accumulated sand and directly to the temperature of such sand, and mixing the water and sand in the mixer.

I3. The method recited in claim 2 in which the measuring is followed and the mixing is preceded by the abrupt and substantially simultaneous discharge of all of the sand and water into the mixer.

4. A method of preparing a batch of foundry sand for use with absolute water requirements at atmospheric temperature, which method comprises the accumulation of a body of sand for use in said batch, measuring the amount of water in said sand and the temperature of said sand, integrating said measurements, accumulating separately an amount of water which is increased from the absolute water requirement at atmospheric temperature in accordance with said integration, and in an amount which is related inversely to initial water content and directly to initial temperature of the body of sand so accumulated, and thereafter dumping the sand and the accumulated water into a mixer and completing the mixing thereof.

S. A method of preparing foundry sand comprising the steps of measuring the temperature of the sand in advance of adding any water thereto, measuring the initial Water content of the sand in advance of adding any water thereto, integrating said measurements and adding to the sand a quantity of water according to said integration, and which quantity is generally proportionate to sand temperature as so measured and inversely proportionate to the water content of the sand as so measured.

6. A method of preparing foundry sand for use with absolute water requirements at atmospheric temperature, said method comprising the steps of measuring the temperature and water content of the sand in advance of final addition of water thereto, integrating said measurements and adding -to the sand a quantity of water determined by said integration and which is in direct proportion to its temperature and in inverse proportion to its Water content, References Cited in the le of this patent and I.ml-.Xilllg With the Sand iileyl/atl SO added. n i UNITED STATES PATENTS 7. A method of preparmg foundry sand comprlslng the steps of measuring the temperature and water content .2r-188398 Smm- 7", Ian' 30 1940 of the sand in advance of nal addition of Water thereto, 2223126 Mclum Feb' 17 1942' integrating said measurements and adding to the sand a 2.2271953 Y Christensen Mar' 311 1942 quantity of water aceordingfto said integration and which quantity is generally proportionatetozsand tempergtuore as FOREIGN PATENTS so measured and inversely proportionate to the water con- 6/003210 Greet Britain A Apr. 2, 1948 tent of the sand as `so measured. 1.0

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.. 2,958, lO'? November l, 1960 l Nelson Hartley It is herebjf certified that error appears in the.printed specification of the above lnumbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 2, line 6, after "View" insert taken column 5, line 6, for "its" read it line 20, for "ot" read mto column 7, line 74, for "is", first occurrence, read as column lO, line 34, for "mositure" read moisture line 39, for "of", first occurrence, read to Signed and sealed this 25th day of April 1961.

(SEAL) Attest:

ERNEST w. SWTDER DAVID L, LADD Attesting Officer` Commissioner of Patents UNITED STATES PATENT OFFICE CERTIFICATE 0F CORRECTION Patent No. 2,958, 107 November l, 1960 Nelson Hartley It is herebjy certified that error appears in the-printed specification of the above `numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 2, line 6, after "View" insert taken column 5, line for "its" read it line 20, for "ot" read to column 7, line 74, for "is", first occurrence, read as column lO, line 34, for "mositure?l read moisture line 39, for "of", first occurrence, read to signed and sealed this 25th day of April 196D (SEAL) Attest:

ERNEST w., SWIDER DAVID L., LADD Attesting Officer Commissioner of Patents 

